Direct Observation of Vortex Shells and Magic Numbers in Mesoscopic Superconducting Disks

TL;DR

This study visualizes vortex arrangements in mesoscopic superconducting disks, revealing shell structures and identifying 'magic' numbers associated with stable vortex configurations using direct imaging techniques.

Contribution

It provides the first direct visualization of vortex shells and magic numbers in mesoscopic superconducting disks, advancing understanding of vortex matter in confined geometries.

Findings

Vortex shells form concentric patterns in mesoscopic disks.

Identification of 'magic' numbers where new vortex shells appear.

Stable and metastable vortex configurations observed across different conditions.

Abstract

We have visualised and studied vortex configurations in mesoscopic superconducting disks using the Bitter decoration technique. For a broad range of vorticities L the circular geometry is found to result in the formation of concentric shells of vortices. From images obtained on disks of different sizes in a range of magnetic fields we were able to trace the evolution of vortex states and identify stable and metastable configurations. Furthermore, quantitative analysis of shell filling with increasing L allowed us to identify 'magic' numbers corresponding to the appearance of consecutive new shells.